catalic is designed for minimizes the risk of exhaust gas
A catalytic exhaust system if I am understanding your question correctly, is basically the exhaust system, comprised of a catalytic converter, O2 sensor, exhaust pipe, and a muffler. Now I'm guessing that you want to know about the catalytic converter, well the converter turns harmful gasses such as Carbon Monoxide into compounds like Carbon Dioxide with the use of catalysts (Differs car to car). It does this at rather high temperatures (I believe it gets to be around 1000F, but don't quote me on that), and it has layers of honeycombed ceramic inside of it to do this. I'm sure you can find a better explanation on pedia or autoblog if this doesn't help.
Any Midas service station, should be able to put them on for ca $20
$25-50 if you can find someone to do it. Walmart does it for $12 per tire when you buy their tire.
Don't ask us, call Wal-Mart, Free Service Tire, something like that.
